A Stable Y(III)-Based Amide-Functionalized Metal-Organic Framework for Propane/Methane Separation and Knoevenagel Condensation.

Here, a Y(III)-based metal-organic framework, {[Y(μ-O)(μ-OH)(HO)(BTCTBA)]·2[(CH)NH]·5DMF·CHCl·4HO}, has been successfully synthesized under solvothermal conditions. was constructed with amide-functionalized tricarboxylate ligands and Y(III)-based infinite chains, where the Y repeating units are arranged in a order. The overall framework could be viewed as a novel (3,5)-connected net with two types of channels along the [100] and [010] directions. possesses a large BET surface area (1553 m g), a permanent pore volume (0.67 cm g), and outstanding thermal and chemical stability, which give potential for the purification of natural gas, especially the equimolar separation of CH/CH with a high selectivity of 176. In addition, benefiting from the amide functional groups as Brønsted basic sites and the exposure of open metal sites as Lewis acid sites after activation, can serve as a high-efficiency heterogeneous catalyst for Knoevenagel condensation by the reactions of malononitrile with benzaldehyde (yield of 98%, turnover number of 392, and turnover frequency of 3.27 min) and diverse aldehyde compounds. A rational mechanism was put forward that the Knoevenagel condensation was catalyzed by the synergistic effect of the Lewis acid sites and Brønsted basic sites, engendering the polarization of the carbonyl groups and the deprotonation of the methylene groups for nucleophilic attack.